1. Field of the Invention
The present invention relates to a gas barrier (meth)acrylate resin cured product, more particularly to a cured product obtained by ultraviolet-curing or heat-curing a (meth)acrylate derivative. The gas barrier (meth)acrylate resin cured product of the present invention is widely applicable to various industrial fields such as coating films for corrosion prevention and decorative finish, packaging materials for foods and medicines which require high gas barrier properties, adhesive layers for laminating films, etc.
2. Description of the Prior Art
Well-known gas barrier materials include polyvinylidene chloride and vinylidene chloride copolymer (hereinafter referred to as “PVDC”). Particularly, coated PVDC films are known as laminated films which are highly barrier against oxygen gas and moisture. Since PVDC is little moisture-absorbent and shows high gas barrier properties under high humidity conditions, PVDC can be coated with various substrate films irrespective of their moisture permeability. With its gas barrier properties, the laminated film is used for packaging various foods irrespective of being dry or wet. After use, these packaging materials are discarded as domestic wastes. However, PVDC generates harmful gas upon combustion and produces highly carcinogenic organic chlorine compounds upon incineration at low temperatures. Therefore, it has been strongly desired to substitute other materials for PVDC.
Polyvinyl alcohol (PVA) films are well known as another gas barrier material free from producing the organic chlorine compounds. PVA films are excellent in oxygen gas barrier properties when the moisture absorption is low. However, PVA films are highly moisture-absorbent and its oxygen gas barrier properties are steeply lowered at a relative humidity exceeding 70% to make PVA films less practical.
It is reported that an amine-cured epoxy resin has gas barrier properties higher than the above composition (polyvinyl alcohol-based (PVA-based) film) and exhibits improved gas barrier properties under high humidity conditions (JP 7-91367B and JP 7-91368B). However, a large amount of non-reacted amine groups having active hydrogen remains in the amine-cured epoxy resin. Therefore, when coated to metal, concrete, etc. to prevent rust and corrosion, there may be problems of failing to obtain excellent functions inherent to epoxy resin such as adhesiveness, heat resistance, chemical resistance and electric characteristics.
Also disclosed are a gas barrier polyurethane resin and a gas barrier film containing it (JP 2000-98047A), a gas barrier laminated stretch film made of a polyurethane thermoplastic elastomer (JP 7-112518A), and a polyurethane composite material having its gas barrier properties improved by a layered clay mineral (JP 10-168305A). However, the proposed compositions are based on thermoplastic resins and not suitable as the coating composition. In addition, the proposed resins are poor in the adhesion to substrate materials. Therefore, when applied to the packaging materials for foods and medicines which require high gas barrier properties, the proposed gas barrier film should be coated with another adhesive on its both sides to, laminate it with substrate films. This increases the production costs of laminated films and complicates the laminating step, and there is some fear for affecting environment due to increased amount of waste which is a recent serious problem.